I'm currently investigating a mail loop issue and would like to know how can I resolved this issue.

Our exchange server has a max. limit of 30hop counts. However when this person (not our client) forwards an email to a distirbution list (postfix) and one of the recipient on that distribution list auto-forwards all mails to to his mailbox here in our exchange server the mail will not arrived in our exchange server. (we cant even find it even with diagnostic logging turned on or in message tracking)

The sender will always received status 4.4.6 this only occurs on the email that is auto-forwarded to our server. Client settings does not have forwarding rules.